The present invention relates to an illuminated switch device, and more particularly to an illuminated switch device capable of changing an illumination color of an indicator in association with the operation of a knob.
This kind of illuminated switch device is widely utilized as an on-vehicle switch. For example, at the same time a vehicle light is turned on, a light source of the switch is designed to be turned on to illuminate the indicator of the knob, so that an operator can easily recognize the indication on the knob even in the night or in the dark such as a tunnel.
FIGS. 5A and 5B show a conventional illuminated switch device proposed by the same applicant, which device is disclosed in Japanese Patent Publication No. 57-35529. Referring to the drawings, reference numeral 1 designates a push-button switch mounted to a metal mounting frame 2. The push-button switch 1 is operated by an operating rod 3. A return coil spring 4 is provided around the operating rod 3 so as to return the push-button switch 1 to a normal or rest position. Reference numeral 5 designates a knob holder formed of synthetic resin. The knob holder 5 has a front opening portion to which a knob 6 is fixed. The knob 6 is formed of a light transmissive resin having an appropriate color. Reference number 7 designates a slider formed of synthetic resin. The slider 7 is integrally formed with an operating arm 7a and a forked tongue 7b. The knob holder 5 is mounted to the front end portion of the slider 7. The slider 7 is slidably mounted in a case 8 formed of synthetic resin. Reference numeral 9 designates a rotatable member having a pair of supporting shafts 9a, a forked tongue 9b and a planar filter 9c formed of a translucent resin. The rotatable member 9 is rotatably supported through the supporting shafts 9a to the case 8. As shown in FIG. 5A under the undepressed condition of the knob 6, the filter 9c is opposed to the tongue 7b of the slider 7. Reference numeral 11 designates a lamp cover for supporting a lamp 12 as a light source. A light transmissive member 10 formed of a light transmissive resin is mounted in the lamp cover 11. A coil spring 13 is interposed between the operating arm 7a and the case 8. The knob holder 5, the knob 6 and the slider 7 constitute a push button.
In operation, the lamp 12 is normally maintained in an on-state irrespective of the position of the knob 6. When the knob 6 is in the undepressed position as shown in FIG. 5A, the light from the lamp 12 is transmitted through both the filter 9c and the knob 6. Accordingly, a quantity of the light is remarkably reduced to dimly illuminate the indicator on the knob 6. On the other hand, when the knob 6 is depressed to displace the slider 7 in a direction of an arrow Y shown in FIG. 5A, the operating rod 3 of the push-button switch 1 is urged by the operating arm 7a of the slider 7 against the biasing force of the coil spring 4. As a result, the push-button switch 1 is turned on. At the same time, the filter 9c of the rotatable member 9 is urged by the tongue 7b of the slider 7 to be rotated as shown in FIG. 5B. As a result, the filter 9c is located outside the light path, while the forked tongue 9b is located in the light path. Under the condition, the light from the lamp 12 is allowed to pass through the vacancy of the forked tongues 7b and 9b, and is transmitted through the knob 6 only. Therefore, the quantity of the light is increased more than that in the condition shown in FIG. 5A, and the indicator on the knob 6 is brightly illuminated.
Thus, the on/off state of the push-button switch 1 can be recognized by the difference in brightness of the illuminated indicator due to a change in the quantity of the light from the lamp 12. Alternatively, in the case that the knob 6 and the filter 9c are colored, the on/off state can be recognized by the difference in tone of the illuminated indicator.
However, the above-mentioned prior art switch device has the following problem. First, as the rotatable member 9 is rotated at 90 degrees by the reciprocation of the slider 7 to thereby selectively locate the filter 9c outside or inside the light path, the rotatable member 9 must be provided in a narrow space within a moving area of the slider 7. Accordingly, the assembly of the rotatable member 9 with the slider 7 is rendered troublesome. Further, there is a possibility that a rotational angle of the rotatable member 9 under the undepressed or depressed condition of the knob 6 will be fluctuated because of a variation in the dimensional accuracy of the parts such as the filter 9c. For example, when the knob 6 is in the depressed position, there is a possibility that the filter 9c will be partially located in the light path, causing ununiformity of the illumination of the indicator.